Incandescent lamps are commonly used for a wide variety of indicator lights. Although these incandescent lamps generally provide good optical performance, they have several significant drawbacks. Namely, incandescent lamps have low reliability and a short life cycle so that replacement is frequently required. These shortcomings can be particularly troublesome when the lamp is mounted in a difficult to access location. The cost of the labor to replace the lamp is often several orders of magnitude greater than the cost of the lamp itself.
Due to the high demand for increased reliability, there have been recent efforts to utilize LEDs as replacements in existing incandescent lamps. The LED is an attractive alternative because of its high reliability and longer life expectancy. Moreover, the LED can also be easily retrofitted into incandescent bulb applications. This approach, however, suffers from poor optical performance when compared to conventional incandescent lamps. The single LED simply does not produce the same amount of light as a single incandescent bulb, and therefore, it is generally necessary to employ a number of LEDs in a cluster to produce the same amount of light. Moreover, the light emitted from most LEDs is highly directional resulting in a narrow effective viewing angle often requiring the viewer to be positioned directly in front of the lamp. Accordingly, there is a current need for a visual indicator lamp with the high reliability of an LED and the optical performance of an incandescent lamp.